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jYeon2061

How do change the triangle shape during runtime

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jYeon2061    122
Hi, I'm very novice at Directx, so it would be nice to get some step by step instructions or an example.
#include <windows.h>
#include <windowsx.h>
#include <d3d9.h>

// define the screen resolution and keyboard macros
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
#define KEY_UP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)

// include the Direct3D Library file
#pragma comment (lib, "d3d9.lib")

// global declarations
LPDIRECT3D9 d3d;    // the pointer to our Direct3D interface
LPDIRECT3DDEVICE9 d3ddev;    // the pointer to the device class
LPDIRECT3DVERTEXBUFFER9 t_buffer = NULL;    // the pointer to the vertex buffer

// function prototypes
void initD3D(HWND hWnd);    // sets up and initializes Direct3D
void render_frame(void);    // renders a single frame
void cleanD3D(void);    // closes Direct3D and releases memory
void init_graphics(void);    // 3D declarations

struct CUSTOMVERTEX {FLOAT X, Y, Z, RHW; DWORD COLOR;};
#define CUSTOMFVF (D3DFVF_XYZRHW | D3DFVF_DIFFUSE)

// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);


// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    HWND hWnd;
    WNDCLASSEX wc;

    ZeroMemory(&wc, sizeof(WNDCLASSEX));

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = CS_HREDRAW | CS_VREDRAW;
    wc.lpfnWndProc = (WNDPROC)WindowProc;
    wc.hInstance = hInstance;
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    // wc.hbrBackground = (HBRUSH)COLOR_WINDOW;    // not needed any more
    wc.lpszClassName = L"WindowClass";

    RegisterClassEx(&wc);

    hWnd = CreateWindowEx(NULL,
                          L"WindowClass",
                          L"Our Direct3D Program",
                          WS_EX_TOPMOST | WS_POPUP,    // fullscreen values
                          0, 0,    // the starting x and y positions should be 0
                          SCREEN_WIDTH, SCREEN_HEIGHT,    // set the window to 640 x 480
                          NULL,
                          NULL,
                          hInstance,
                          NULL);

    ShowWindow(hWnd, nCmdShow);

    // set up and initialize Direct3D
    initD3D(hWnd);

    // enter the main loop:

    MSG msg;

    while(TRUE)
    {
        DWORD starting_point = GetTickCount();

        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
                break;

            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        render_frame();

        // check the 'escape' key
        if(KEY_DOWN(VK_ESCAPE))
            PostMessage(hWnd, WM_DESTROY, 0, 0);

        while ((GetTickCount() - starting_point) < 25);
    }

    // clean up DirectX and COM
    cleanD3D();

    return msg.wParam;
}


// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_DESTROY:
            {
                PostQuitMessage(0);
                return 0;
            } break;
    }

    return DefWindowProc (hWnd, message, wParam, lParam);
}


// this function initializes and prepares Direct3D for use
void initD3D(HWND hWnd)
{
    d3d = Direct3DCreate9(D3D_SDK_VERSION);

    D3DPRESENT_PARAMETERS d3dpp;

    ZeroMemory(&d3dpp, sizeof(d3dpp));
    d3dpp.Windowed = FALSE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hWnd;
    d3dpp.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dpp.BackBufferWidth = SCREEN_WIDTH;
    d3dpp.BackBufferHeight = SCREEN_HEIGHT;

    // create a device class using this information and the info from the d3dpp stuct
    d3d->CreateDevice(D3DADAPTER_DEFAULT,
                      D3DDEVTYPE_HAL,
                      hWnd,
                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,
                      &d3dpp,
                      &d3ddev);

    init_graphics();    // call the function to initialize the triangle

    return;
}


// this is the function used to render a single frame
void render_frame(void)
{
    d3ddev->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);

    d3ddev->BeginScene();

        // select which vertex format we are using
        d3ddev->SetFVF(CUSTOMFVF);

        // select the vertex buffer to display
        d3ddev->SetStreamSource(0, t_buffer, 0, sizeof(CUSTOMVERTEX));

        // copy the vertex buffer to the back buffer
        d3ddev->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);

    d3ddev->EndScene();

    d3ddev->Present(NULL, NULL, NULL, NULL);

    return;
}


// this is the function that cleans up Direct3D and COM
void cleanD3D(void)
{
    t_buffer->Release();    // close and release the vertex buffer
    d3ddev->Release();    // close and release the 3D device
    d3d->Release();    // close and release Direct3D

    return;
}


// this is the function that puts the 3D models into video RAM
void init_graphics(void)
{
    // create the vertices using the CUSTOMVERTEX struct
    CUSTOMVERTEX t_vert[] =
    {
        { 320.0f, 50.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 0, 255), },
        { 520.0f, 400.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 255, 0), },
        { 120.0f, 400.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(255, 0, 0), },
    };

    // create a vertex buffer interface called t_buffer
    d3ddev->CreateVertexBuffer(3*sizeof(CUSTOMVERTEX),
                               0,
                               CUSTOMFVF,
                               D3DPOOL_MANAGED,
                               &t_buffer,
                               NULL);

    VOID* pVoid;    // a void pointer

    // lock t_buffer and load the vertices into it
    t_buffer->Lock(0, 0, (void**)&pVoid, 0);
    memcpy(pVoid, t_vert, sizeof(t_vert));
    t_buffer->Unlock();

    return;
}
I've been told to use the void pointer or something..?? I still can't figure out what to do.

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littlekid    229
In my opinion, one way which you can approach it is to make the VB dynamic and update or add them at each frame:

you lock your dynamic VB and modify or add vertices
unlock the VB
render with the new correct parameters.
Hence you can make your triangle become a octagon by adding and adjusting the points.

Or if you are just looking to scale, skew, rotate, translate your triangle, you can input the proper world matrix to adjust the triangle.

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Evil Steve    2017
Yep, updating the VB is the way to go.

A bit off-topic, there's loads of things wrong with that code (I can see 11 problems in that code snippet), some of them quite serious. I'd strongly recommend binning whatever book that code is from, or finding a new website to learn from.

Out of interest, where is it from? I really hope it's not another DirectXTutorial mess...

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mickeyren    132
its wise to tell DirectX that when you're handling dynamic VB is to set the usage flag when creating the vertex buffer to D3DUSAGE_DYNAMIC. The SDK documentation will tell you more about the other various usage. (search for the topic Performance Optimizations (Direct3D 9) )

Hope that helps.

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Treb    172
What are you trying to do exactly? You may be able to write a shader for it and not have to worry about dynamic buffers.

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Googol PL3X    100
That code is fairly horrible, your programming could be crashing down around you and you wouldn't even know it, when ever creating an object, loading from file ect CHECK TO SEE IF IT ACTUALLY WORKED. For example, this bit


hWnd = CreateWindowEx(NULL,

L"WindowClass",

L"Our Direct3D Program",

WS_EX_TOPMOST | WS_POPUP, // fullscreen values

0, 0, // the starting x and y positions should be 0

SCREEN_WIDTH, SCREEN_HEIGHT, // set the window to 640 x 480

NULL,

NULL,

hInstance,

NULL);





Would be safer if you added this after:



if (hWnd == NULL)
{
return E_FAIL;
}

or

if (hWnd == NULL)
{
MessageBox( g_hWnd, "Unable to Create Window", "Error", MB_ICONINFORMATION );
}


It's very important to check for these kinds of errors, for example, if something is missing and your program continues to run, you could get all sorts or errors from odd looking graphics, bad performance to a slightly more extreme case of a system crash.

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